Why can I see my IR port light up when transferring data?

[MWink]

Today I wanted to install some software on my Palm IIIc but I didn't have my cradle so I decided to try syncing it using my laptops IR port. The sync went just fine but I noticed that I could see the LED's in the Palm and the laptop blinking when transferring data. I thought the human eye couldn't see infrared light. What was I seeing?

 

[Hayabusa Rider]

It means you are really a bat.

 

[Sketcher]

It's not IR light you're seeing.

It's a built in LED indicator to allow visual verification that some form of data recognition is taking place.

 

[Wallydraigle]

Cause they used an LED that emits others wavelengths besides IR? Maybe it was cheaper.

 

[Hayabusa Rider]

Ok Ok

j/k

 

[MWink]

Originally posted by: Sketcher
It's not IR light you're seeing.

It's a built in LED indicator to allow visual verification that some form of data recognition is taking place.

IMO, that doesn't really make sense. Why would they put a very dim LED IN the IR port itself. Also, I think there is only one LED in each device. Both devices lit up a very faint purple when transmitting data and I could only see it if I looked almost directly into the IR port.

Cause they used an LED that emits others wavelengths besides IR? Maybe it was cheaper.

This sounds much more plausible.

 

[iamme]

maybe Cyclops from the X-Men got his powers by staring at his IR port too long....

🙂

 

[BennyD]

Originally posted by: iamme
maybe Cyclops from the X-Men got his powers by staring at his IR port too long....

🙂

maybe a radioactive IR port 😛

 

[iamme]

Originally posted by: BennyD

Originally posted by: iamme
maybe Cyclops from the X-Men got his powers by staring at his IR port too long....

🙂

maybe a radioactive IR port 😛

i wonder if i aimed a Sony Clie at his face, i could beam his thoughts....before i got fried, of course 🙂

 

[The Stigenator]

i have seen that too.. a faint purple on IR ports.. notsure what causes it but I think its that cover that's on teh IR port.. cause i cant see it on my television controller which has nothing covering the IRled.

the remote control watch for tv / cable box has an red led that lights up everytime you hit a button on it that transmits IR signals.

 

[Eli]

Purple?

You do realize that purple and red are on the opposite ends of the spectrum? lol...

 

[Sketcher]

Cha Ching!!

Intro to IrDA

Introduction to IrDA
IrDA is a standard defined by the IrDA consortium (Infrared Data Association). It specifies a way to wirelessly transfer data via infrared radiation. The IrDA specifications include standards for both the physical devices and the protocols they use to communicate with each other. The IrDA standards have arised from the need to connect various mobile devices together. (Primary use for IrDA is to link notebooks or various personal communicators; however, even video cameras are sometimes equipped with an IrDA interface.)
IrDA devices communicate using infrared LED's. Wavelength used is 875 nm +- production tolerance (around 30 nm). Many CCD cameras are sensitive to this wawelength too. Receivers utilize PIN photodiodes in generation mode (incoming light "kicks out" electrons. Signal continues into a filter. Only allowed frequencies for a particular IrDA modulation can pass through.) There is a direct relationship between the energy of the incoming radiation, and the charge that the optics part of the receiver generates.

What IR is

Light with wavelengths from 0.7 micron to about 0.1 millimeter is called infrared light. The band of infrared light is a thousand times wider than that of visible light. All of it is invisible to our eyes. Infrared films and normal video cameras are sensitive to what is called very near infrared light (0.7 to 0.9 microns). This is also the type of light that the remote control for your TV uses. (Try shining your remote control at your video camera.) Beyond those waves are the near infrared waves at 2.4 microns that the South Pole Infrared Explorer (SPIREX) telescope observes from the South Pole. SPIREX uses a very special video still-frame camera that can detect and make images of stars that emit this "color" of light. Longer wavelength infrared light is emitted by hot objects in our world. So, although we can't see the thermal infrared light from a hot piece of metal like a soldering iron, we can feel it on our skin when we bring our hand close. Scientists use many types of devices to detect and measure infrared light. Even if we can't see it with our eyes through a telescope our specialized astronomical cameras can.

 

[MWink]

Sketcher, that's interesting and all but how does it answer my original question? I know I shouldn't be able to see infrared light, but what AM I seeing?

 

[Harvey]

Why can I see my IR port light up when transferring data?

It uses an LED that emits IR which, by definition, is beyond the red range the human eye can see.

Either that or, in your case, the lights are on, but nobody's home. 😉

The other end of of the spectrum is ultra-violet (UV), which you can't see, either, but it can give you a hell of a sunburn.

 

[Sketcher]

Originally posted by: MWink
Sketcher, that's interesting and all but how does it answer my original question? I know I shouldn't be able to see infrared light, but what AM I seeing?

It answers your question by proving that it's not the IR light you are seeing. The light you see is actually an enhancement indicator to visually acknowledge that data transfer is taking place. Some hardware use dual optics which also perform visual functions. Others have separate indicators which read IR signals and display accordingly. The color of the indicator is irrelevant as any color of lense, shield or LED can be used.